[Patch][CLA] Dijit: Calendar missing aria role and summary

[mikeb]

dijit.Calendar and CalendarLite? use role="columnheader". However, the required context for a columnheader is a parent with the role="row". (​http://www.w3.org/TR/wai-aria/roles#columnheader). The <tr elements in the thead need role="row".

Also, no meaningful summary for the table is provided that describe the purpose of the table. This is getting picked up by our automated tools because the header cells of the calendar (week days) are not in the first row of the table.

Generally it is the responsibility of the developer using the calendar widget to provide enough information on the page for the user to understand that they are interacting with a calendar. We don't want to add a generic summary attribute to the calendar that says, "calendar" as this would be annoying for JAWS users to hear each time they used the calendar.

In lieu of this I think Dojo should just provide a default empty summary attribute. This encourages developers to use the summary if they deem is appropriate for their users.

[bill]

Specify summary to Calendar will already apply it to the this.domNode, but I'll checkin the role fix.

[bill]

In [28437]:

Add aria role, fixes #15257, thanks Mike !strict.